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Given that fall is just around the corner and those of us who live in northern latitudes are heading back into the seasons where we will have little to no chance to get natural vitamin D from the sun, I am revisiting a story I wrote more than a year ago: Vitamin D: Pros and Cons.

Vitamin d hype and debate continue

This past spring, large ads in Canadian newspapers claimed that no one is getting anywhere close to the amount of vitamin D needed and that we should increase our intake by 10-fold, from the 600-800 international units daily recommended by Health Canada (and the US Institute of Medicine), to a whopping 6,000-9,000 international units per day.

Canadian registered dietician Leslie Beck wrote in The Globe and Mail, “Osteoporosis experts are being inundated with calls from confused patients. Dietitians of Canada has expressed its concern in a letter to Health Canada. And Canadians are wondering what to make of the bold assertion that Health Canada was wrong and that we actually need more – a whole lot more – vitamin D to ward off disease. Do we?”

Those ads, placed by Pure North S’Energy Foundation, claimed that vitamin D deficiency is causing widespread illnesses and premature deaths. According to this story in The Globe and Mail, wealthy entrepreneur and chemical engineer Allan Markin, who claims he has invested $20 million in Pure North S’Energy Foundation, personally takes 12,000 IUs of vitamin D daily.

Measuring media hype about vitamin D

In a recent paper, Timothy Caulfield and colleagues examined the media coverage of vitamin D and how its role in health and the need for supplements were portrayed. Caulfield is a Canada Research Chair in Health Law and Policy and a Professor in the Faculty of Law and the School of Public Health at the University of Alberta. The paper was published in BMJ Open and a full copy is available here. The researchers surveyed 294 print articles from elite newspapers in the UK, US and Canada over a 5-year period and found that newspaper coverage generally:

supported supplementation for the general population

framed vitamin D as difficult to obtain from the food supply

asserted that vitamin D deficiency is a widespread public health issue

linked vitamin D to a wide range of health conditions for which there is no conclusive scientific evidence

downplayed the limitations of the existing science

overlooked the potential risks of supplementation

It’s no surprise to me that these researchers found 40 different health conditions mentioning a relationship to vitamin D. As I wrote a year ago, there is a flood of observational studies linking vitamin D deficiency to cancer, diabetes, cardiovascular diseases, autism, kidney disease, multiple sclerosis, chronic obstructive pulmonary disease, asthma, gum disease, arthritis, premenstrual syndrome, all-cause mortality and on it goes.

Health journalist André Picard wrote in The Globe and Mail that claims about vitamin D being a miracle drug that can prevent a wide range of illnesses are ridiculous: “These are preposterous claims based on the dubious premise that by hiking the amount of vitamin D in our blood, a broad range of illness would disappear,” and “the fundamental error here is confusing correlation and causation. Yes, people with adequate vitamin D levels have less disease. But it does not follow that pumping everyone full of supplements will make them healthier. Enthusiasm for this panacea simply doesn’t match the scientific evidence.”

Correlation is not causation. Still!

Yes indeed! As any health journalist worth their salt understands, the problem with observational studies is that we only learn that two things changed when we looked at their data together, NOT that changes in one of them caused changes in the other. [If you want to better understand how ridiculous it is to draw causal conclusions on observational data, check out Tyler Vigen’s Spurious Correlations, which started as a blog and is now available as a book. It’s hilarious!]

No matter how much readers or editors want to read about “dramatic new studies” to justify their beliefs that popping large amounts of vitamin D daily will improve their health or ward off a host of diseases, the truth is that answers about vitamin D’s effectiveness and safe upper intake levels can never be found in observational studies. Nor can we discern how much vitamin D people should take based on how far away from the equator they live (yes, that was a real question I was asked to field).

Best evidence on the horizon

So where do things stand? As far as I can tell, the same as they did a year ago. There is still no conclusive evidence that taking vitamin D supplements provides benefits beyond bone health — yet.

JoAnn Manson, MD, DrPH, Chief of Preventative Medicine at Brigham and Women’s Hospital and Professor of Medicine at Harvard Medical School (and who was on the IOM Committee that developed the current public health recommendations) said a year ago that the enthusiasm for vitamin D supplementation continues to outpace the evidence. She said that the evidence to date shows some vitamin D is good, but more is not necessarily better. There is limited research on long-term intakes above 2,000 IU daily and with very high doses of 10,000 IU daily or higher, people can develop a high level of calcium in the blood or urine, which can cause cardiovascular problems and kidney stones.

The best evidence on the horizon, as far as I can tell, is still the VITAL study (VITamin D and OmegA-3 Trial). Led by Dr. Manson and colleague Julie Buring, ScD, it’s a large-scale, randomized, double-blind, placebo-controlled prospective trial with an impressive design. The test groups and the comparison groups are designed to have a large enough difference in vitamin D levels to see if there is a meaningful difference in health outcomes. The study began in 2008 and results are expected in late 2017. I’m optimistic that this study will shed light on understanding how altering levels of vitamin D supplementation impacts on health conditions beyond bone health.

It may not be palatable for those looking for a panacea to wait until late 2017, but strong, evidence-based science takes time.

The PSA test is a blood test that measures the level of prostate-specific antigen, a protein produced by the prostate gland. In very general terms, the higher the PSA level, the more likely it is that a man has prostate cancer.

The controversy about whether healthy men should have a PSA test still rages because the test has a wide margin of error at both ends of the false alarm scale — false positives that may lead to unnecessary treatments like biopsies, and then radiation, chemotherapy and/or surgery; and false negatives that lead to unnecessary deaths because the cancer wasn’t found in time.

What causes false positives? Elevated PSA levels can be caused by things that are not cancer, such as benign prostatic hyperplasia (non-cancerous enlargement of the prostate), inflammation from riding a bicycle, a urinary tract infection, or ejaculation within 2 days prior to the test. At the other end of the scale, false negatives can happen because prostate cancer doesn’t always cause an elevated PSA level in the blood.

Richard J. Amblin, the researcher who discovered prostate-specific antigen in 1970, said in an op-ed in the New York Times in 2010 that the PSA test is “a hugely expensive public health disaster,” and is “hardly more effective than a coin toss.” Recently, health journalist André Picard weighed the pros and cons of the test in The Globe and Mail and said, “Almost all the 23,600 men diagnosed with prostate cancer this year will be convinced that testing saved their lives. The reality is a tad more complicated. We have a lousy test, and physicians and their patients must decide how much stock to put in it.”

So while it may be tempting to abandon the test altogether, the men who were lucky to find an aggressive cancer and treat it in time because their PSA test indicated trouble brewing are certainly not going to agree with statisticians on the cost/benefit tradeoffs of public health screening. According to the Canadian Cancer Society, one in 8 Canadian men will develop prostate cancer in their lifetimes. In 2014 alone, 23,600 men will be diagnosed with prostate cancer and 4,000 men will die from the disease.

Dr. Rajiv Singal, head of the urology division at Toronto East General Hospital and Medcan’s director of urology writes that abandoning the PSA test outright is a short-sighted mistake. He advocates instead for baseline testing followed by “smart screening” at intervals that make sense to see how PSA score changes over time, and taking other risk factors into account, such as family history and ethnic background. This makes sense, especially because the PSA is only a blood test, a rough indication, and not a commitment to anything further.

For now, the best the PSA test can offer is a starting point for a conversation with a doctor about the best course of action at the beginning of a decision tree. For many men, that will mean active surveillance, also called watchful waiting, rather than jumping immediately to treatments and therapies. For others, the appropriate plan of action will depend on their symptoms, age, family history, ethnic background and personal preferences for the wide variety of therapies and treatments that are now available.

The PSA test has another problem: It cannot distinguish between aggressive, fast-growing cancer that needs treatment, and the more common indolent, or slow-growing cancer that may not require any treatment at all.

So what’s on the horizon for finding a better diagnostic tool for prostate cancer?

Dr. Singal says, “An ideal screening test is one that will detect a cancer at a point where intervention will alter the natural history of the disease and where that treatment can be performed safely and in a cost-effective manner.”

It’s that sweet spot that researchers around the globe are pursuing. For example, here are two promising, non-invasive avenues of research for better prostate cancer detection and characterization:

Gene variants. An international research team announced September 15, 2014 that they have found 23 new genetic variants associated with a greater risk of prostate cancer, bringing the total known to 100. The work moving forward will be to translate these findings into a reliable diagnostic blood or urine test that can be used for public health screening. As I reported in my story three years ago, two researchers at the University of Michigan developed a two-gene DNA urine test that can detect two biomarkers found in 95% of prostate cancers called PCA3 and TMPRSS2:ERG gene fusion. I’m not sure why, but it appears the PCA3 test was commercialized alone, to be used together with a PSA test, and was approved by both the FDA and Health Canada. In Canada, the test is not widely available yet, but hopefully will be soon.

Better imaging techniques. In the UK, professor Mark Emberton is studying the effectiveness of multi-parametric magnetic resonance imaging (mpMRI) to detect and characterize prostate cancer before biopsy and then help guide biopsy if required. An mpMRI consists of three different types of high definition images that together provide a better picture of prostate gland tissue. The PROMIS trial has been underway since 2012 and is targeted to finish in 2015. The study design indicates they will also evaluate the economics of using this imaging technique. This 2013 paper in Prostate Cancer and Prostatic Disease (Nature Publishing Group) concluded that mpMRI showed encouraging diagnostic performance to detect and rule out clinically significant prostate cancer in men at risk, before biopsy was performed.

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